Providing leak-proof seals is a continuing problem for any type of system which involves fluids. Exemplary of such systems are hydraulic systems in which hydraulic oil is pressurized in pumps, motors and hydraulic cylinders. In order to keep these devices from leaking hydraulic fluid, it is necessary to have seal integrity, which may be compromised as pressures increase.
One example of hydraulic devices in which leakage has been a problem are hydraulic gear pumps in which meshing gear teeth provide impellers, which when rotated, increase hydraulic pressures by substantial amounts. The impellers are mounted on shafts supported by bearings and sealed by contact seals which engage the shafts along sealing portions thereof. It has been found that these seals leak hydraulic fluid when the fluid is at high pressures.
When the shafts which mount the impellers are machined, residual spiraling tool marks are created by the turning operation. These spiraling tool marks provide paths for hydraulic fluid to flow out of the pump into the surrounding environment not only creating a mess but also creating possible hazards. In addition, microscopic spiraling patterns also occur with a typical cylindrical grinding process. The spiraling pattern created during grinding also provides a leak path for hydraulic fluid.
In addition to hydraulic components having rotating shafts, hydraulic components having sliding shafts, such as hydraulic cylinders, are also confronted with leakage problems when operated at high pressures.